1. Field of the Invention
This invention relates to a transmission system for a self-propelled vehicle with variable travel speed, such as a mowing tractor, its control device as well as a vehicle equipped with such a transmission system.
2. Description of the Related Art
It relates more particularly to a transmission system for a self-propelled vehicle with variable travel speed of the type comprising, between the primary driving shaft of the vehicle and an output shaft, such as the wheel drive shaft of the vehicle, at least one controlled variable speed drive with a belt and a controlled mechanism for reversing the direction of travel of the vehicle, the primary driving shaft transmitting, via the variable speed drive, its motion to the input shaft of the reversal mechanism, itself able to directly or indirectly engage with an output shaft, such as the wheel drive shaft of the vehicle, in such a way as to allow movement forward or in reverse respectively, at a variable travel speed.
Small self-propelled vehicles of the mowing tractor or snowplow type have been extensively developed commercially during recent years. Generally, such self-propelled vehicles are equipped, on the one hand, with a control device for changing the speed, and, on the other hand, with a control device for reversing the direction of travel of the vehicle, these control devices being separate control devices. For the operator, this results in the necessity of manipulating, on the one hand, the direction reversal control device when he wishes to reverse the direction of the vehicle, on the other hand, the speed changing control device when he wishes to change the speed of the vehicle. The presence of two differentiated control devices can lead, in certain cases, to operator handling errors when the order of actuating the different control devices is not observed. If the self-propelled vehicle is equipped with a nonprogressive clutch mechanism or mechanisms, in case of a mishandling by the operator, violent jerking, or even the risk of breaking the transmission, results when the direction is reversed. To avoid such problems, at present self-propelled vehicles are for the most part equipped with a progressive-type clutch mechanism or mechanisms. This leads to an increase in the cost of such vehicles.